Jan I of Bohemia

Jan I of Bohemia (died 1086) was the rebellious ruler of Bohemia, who led an uprising against the Holy Roman Empire in 1080. Jan holed up in Prague and increased the defenses with Slav Levies and crossbowmen, and nearly defeated the German army of Maximillian Mandorf sent to crush him in 1086. However, he was killed and the kingdom of Bohemia conquered. Over 18,000 Bohemians were massacred as retaliation.